Note

For the latest version of this manual associated with this
Yocto Project release, see the
Yocto Project Quick Start
from the Yocto Project website.

Welcome!

Welcome to the Yocto Project!
The Yocto Project is an open-source collaboration project focused on
embedded Linux developers.
Among other things, the Yocto Project uses a build system based on the
OpenEmbedded (OE) project, which uses the
BitBake
tool, to construct complete Linux images.
The BitBake and OE components are combined together to form
Poky,
a reference build system.

If you don't have a system that runs Linux and you want to give the Yocto Project a test run,
you might consider using the Yocto Project Build Appliance.
The Build Appliance allows you to build and boot a custom embedded Linux image with the Yocto
Project using a non-Linux development system.
See the Yocto
Project Build Appliance for more information.

On the other hand, if you know all about open-source development, Linux development environments,
Git source repositories and the like and you just want some quick information that lets you try out
the Yocto Project on your Linux system, skip right to the
"Super User" section at the end of this quick start.

For the rest of you, this short document will give you some basic information about the environment and
let you experience it in its simplest form.
After reading this document, you will have a basic understanding of what the Yocto Project is
and how to use some of its core components.
This document steps you through a simple example showing you how to build a small image
and run it using the Quick EMUlator (QEMU emulator).

For more detailed information on the Yocto Project, you should check out these resources:

Website: The Yocto Project Website
provides the latest builds, breaking news, full development documentation, and a rich Yocto
Project Development Community into which you can tap.

FAQs: Lists commonly asked Yocto Project questions and answers.
You can find two FAQs: Yocto Project FAQ on
a wiki, and the
"FAQ" chapter in
the Yocto Project Reference Manual.

Introducing the Yocto Project Development Environment

The Yocto Project through the OpenEmbedded build system provides an open source development
environment targeting the ARM, MIPS, PowerPC and x86 architectures for a variety of
platforms including x86-64 and emulated ones.
You can use components from the Yocto Project to design, develop, build, debug, simulate,
and test the complete software stack using Linux, the X Window System, GNOME Mobile-based
application frameworks, and Qt frameworks.

The Yocto Project Development Environment

Here are some highlights for the Yocto Project:

Provides a recent Linux kernel along with a set of system commands and libraries suitable for the embedded environment.

Makes available system components such as X11, GTK+, Qt, Clutter, and SDL
(among others) so you can create a rich user experience on devices
that have display hardware.
For devices that do not have a display or where you wish to use alternative UI
frameworks, these components need not be installed.

Creates a focused and stable core compatible with the OpenEmbedded
project with which you can easily and reliably build and develop.

Fully supports a wide range of hardware and device emulation through the QEMU
Emulator.

The Yocto Project can generate images for many kinds of devices.
However, the standard example machines target QEMU full-system emulation for x86, x86-64, ARM, MIPS,
and PPC-based architectures as well as specific hardware such as the
Intel® Desktop Board DH55TC.
Because an image developed with the Yocto Project can boot inside a QEMU emulator, the
development environment works nicely as a test platform for developing embedded software.

Another important Yocto Project feature is the Sato reference User Interface.
This optional GNOME mobile-based UI, which is intended for devices with
restricted screen sizes, sits neatly on top of a device using the
GNOME Mobile Stack and provides a well-defined user experience.
Implemented in its own layer, it makes it clear to developers how they can implement
their own user interface on top of a Linux image created with the Yocto Project.

What You Need and How You Get It

You need these things to develop projects in the Yocto Project
environment:

A host system running a supported Linux distribution
(i.e. recent releases of Fedora, openSUSE, CentOS, Debian,
and Ubuntu).
If the host system supports multiple cores and threads, you can configure the
Yocto Project build system to decrease the time needed to build images
significantly.

The right packages.

A release of the Yocto Project.

The Linux Distribution

The Yocto Project team is continually verifying more and more Linux
distributions with each release.
In general, if you have the current release minus one of the following
distributions you should have no problems.

Ubuntu

Fedora

openSUSE

CentOS

Debian

For a more detailed list of distributions that support the Yocto Project,
see the
"Supported Linux Distributions" section
in the Yocto Project Reference Manual.

The OpenEmbedded build system should be able to run on any modern
distribution that has the following versions for Git, tar, and
Python.

Git 1.7.5 or greater

tar 1.24 or greater

Python 2.7.3 or greater excluding Python
3.x, which is not supported.

Earlier releases of Python are known to not work and the
system does not support Python 3 at this time.
If your system does not meet any of these three listed
version requirements, you can
take steps to prepare the system so that you can still use the build
system.
See the
"Required Git, tar, and Python Versions"
section in the Yocto Project Reference Manual for information.

This document assumes you are running one of the previously noted
distributions on your Linux-based host systems.

Note

If you attempt to use a distribution not in the above list,
you may or may not have success.
Yocto Project releases are tested against the stable Linux
distributions listed in the
"Supported Linux Distributions"
section of the Yocto Project Reference Manual.
If you encounter problems, please go to
Yocto Project Bugzilla
and submit a bug.
We are interested in hearing about your experience.

The Packages

Packages and package installation vary depending on your development system
and on your intent.
For example, if you want to build an image that can run
on QEMU in graphical mode (a minimal, basic build
requirement), then the number of packages is different than if you want to
build an image on a headless system or build out the Yocto Project
documentation set.
Collectively, the number of required packages is large
if you want to be able to cover all cases.

Note

In general, you need to have root access and then install the
required packages.
Thus, the commands in the following section may or may not work
depending on whether or not your Linux distribution has
sudo installed.

The next few sections list, by supported Linux Distributions, the required
packages needed to build an image that runs on QEMU in graphical mode
(e.g. essential plus graphics support).

Note

Depending on the CentOS version you are using, other requirements
and dependencies might exist.
For details, you should look at the CentOS sections on the
Poky/GettingStarted/Dependencies
wiki page.

Yocto Project Release

It is recommended that you get the latest Yocto Project files
by setting up (cloning in
Git terms) a local
copy of the
poky Git repository on your host development
system.
Doing so allows you to contribute back to the Yocto Project project.
For information on how to get set up using this method, see the
"Yocto
Project Release" item in the Yocto Project Development Manual.

You can also get the Yocto Project Files by downloading
Yocto Project releases from the
Yocto Project website.
From the website, you just click "Downloads" in the navigation pane
to the left to display all Yocto Project downloads.
Current and archived releases are available for download.
Nightly and developmental builds are also maintained at
http://autobuilder.yoctoproject.org/nightly/.
However, for this document a released version of Yocto Project is used.

A Quick Test Run

Now that you have your system requirements in order, you can give the Yocto Project a try.
This section presents some steps that let you do the following:

Build an image and run it in the QEMU emulator.

Use a pre-built image and run it in the QEMU emulator.

Building an Image

In the development environment you will need to build an image whenever you change hardware
support, add or change system libraries, or add or change services that have dependencies.

Building an Image

Use the following commands to build your image.
The OpenEmbedded build process creates an entire Linux distribution, including the toolchain,
from source.

Note

The build process using Sato currently consumes about 50GB of disk space.
To allow for variations in the build process and for future package expansion, we
recommend having at least 50 Gbytes of free disk space.

Tip

To help conserve disk space during builds, you can add the
following statement to your project's configuration file,
which for this example is
poky/build/conf/local.conf.
Adding this statement deletes the work directory used for
building a package once the package is built.

INHERIT += "rm_work"

In the previous example, the first command uses
Git to create
a local repository named poky that is a
clone of the upstream Yocto Project
poky repository.

The third command checks out a local branch and
names it daisy.
The local branch tracks the upstream branch of the same name.
Creating your own branch based on the released branch ensures
you are using the latest files for that release.

The final command runs the Yocto Project
oe-init-build-env
environment setup script.
Running this script defines OpenEmbedded build environment
settings needed to complete the build.
The script also creates the
Build Directory,
which is build in this case and is located
in the
Source Directory.
After the script runs, your current working directory is set
to the Build Directory.
Later, when the build completes, the Build Directory contains
all the files created during the build.

Note

Take some time to examine your local.conf file
in your project's configuration directory, which is found in the Build Directory.
The defaults in that file should work fine.
However, there are some variables of interest at which you might look.

By default, the target architecture for the build is qemux86,
which produces an image that can be used in the QEMU emulator and is targeted at an
Intel® 32-bit based architecture.
To change this default, edit the value of the
MACHINE
variable in the configuration file before launching the build.

Another couple of variables of interest are the
BB_NUMBER_THREADS and the
PARALLEL_MAKE variables.
By default, these variables are set to how ever many processor
cores your build host uses.
However, if your build host uses multiple processor cores,
you should increase these settings to twice the number of
cores used.
Doing so can significantly shorten your build time.

Another consideration before you build is the package manager used when creating
the image.
By default, the OpenEmbedded build system uses the RPM package manager.
You can control this configuration by using the
PACKAGE_CLASSES variable.
For additional package manager selection information, see the
"package*.bbclass"
section in the Yocto Project Reference Manual.

Continue with the following command to build an OS image for the target, which is
core-image-sato in this example.
For information on the -k option use the
bitbake --help command, see the
"BitBake"
section in the Yocto Project Reference Manual, or see the
"BitBake Command"
section in the BitBake User Manual.

$ bitbake -k core-image-sato

Note

BitBake requires Python 2.6 or 2.7. For more information on
this requirement, see the
"Required Git, tar, and Python"
section in the Yocto Project Reference Manual.

The final command runs the image:

$ runqemu qemux86

Note

Depending on the number of processors and cores, the amount
of RAM, the speed of your Internet connection and other
factors, the build process could take several hours the
first time you run it.
Subsequent builds run much faster since parts of the build
are cached.

Using Pre-Built Binaries and QEMU

If hardware, libraries and services are stable, you can get started by using a pre-built binary
of the filesystem image, kernel, and toolchain and run it using the QEMU emulator.
This scenario is useful for developing application software.

Using a Pre-Built Image

For this scenario, you need to do several things:

Install the appropriate stand-alone toolchain tarball.

Download the pre-built image that will boot with QEMU.
You need to be sure to get the QEMU image that matches your target machine’s
architecture (e.g. x86, ARM, etc.).

Download the filesystem image for your target machine's architecture.

Set up the environment to emulate the hardware and then start the QEMU emulator.

Installing the Toolchain

You can download a tarball installer, which includes the
pre-built toolchain, the runqemu
script, and support files from the appropriate directory under
http://downloads.yoctoproject.org/releases/yocto/yocto-1.6.1/toolchain/.
Toolchains are available for 32-bit and 64-bit x86 development
systems from the i686 and
x86_64 directories, respectively.
The toolchains the Yocto Project provides are based off the
core-image-sato image and contain
libraries appropriate for developing against that image.
Each type of development system supports five or more target
architectures.

The names of the tarball installer scripts are such that a
string representing the host system appears first in the
filename and then is immediately followed by a string
representing the target architecture.

poky-eglibc-<host_system>-<image_type>-<arch>-toolchain-<release_version>.sh
Where:
<host_system> is a string representing your development system:
i686 or x86_64.
<image_type> is a string representing the image you wish to
develop a Software Development Toolkit (SDK) for use against.
The Yocto Project builds toolchain installers using the
following BitBake command:
bitbake core-image-sato -c populate_sdk
<arch> is a string representing the tuned target architecture:
i586, x86_64, powerpc, mips, armv7a or armv5te
<release_version> is a string representing the release number of the
Yocto Project:
1.6.1, 1.6.1+snapshot

For example, the following toolchain installer is for a 64-bit
development host system and a i586-tuned target architecture
based off the SDK for core-image-sato:

poky-eglibc-x86_64-core-image-sato-i586-toolchain-1.6.1.sh

Toolchains are self-contained and by default are installed into
/opt/poky.
However, when you run the toolchain installer, you can choose an
installation directory.

The following command shows how to run the installer given a toolchain tarball
for a 64-bit x86 development host system and a 32-bit x86 target architecture.
You must change the permissions on the toolchain
installer script so that it is executable.

The example assumes the toolchain installer is located in ~/Downloads/.

Note

If you do not have write permissions for the directory into which you are installing
the toolchain, the toolchain installer notifies you and exits.
Be sure you have write permissions in the directory and run the installer again.

The filesystem image has two tarball forms: ext3 and
tar.
You must use the ext3 form when booting an image using the
QEMU emulator.
The tar form can be flattened out in your host development system
and used for build purposes with the Yocto Project.

Continuing with the example, the following two commands setup the emulation
environment and launch QEMU.
This example assumes the root filesystem (.ext3 file) and
the pre-built kernel image file both reside in your home directory.
The kernel and filesystem are for a 32-bit target architecture.

The environment in which QEMU launches varies depending on the filesystem image and on the
target architecture.
For example, if you source the environment for the ARM target
architecture and then boot the minimal QEMU image, the emulator comes up in a new
shell in command-line mode.
However, if you boot the SDK image, QEMU comes up with a GUI.

Note

Booting the PPC image results in QEMU launching in the same shell in
command-line mode.

Super User

This section
[1]
gives you a minimal description of how to use the Yocto Project to build
images for Beaglebone hardware starting from scratch.
The steps were performed on a 64-bit Ubuntu 12.04 system that
has four cores.

Getting the Yocto Project

Set up your
Source Directory
by using Git to clone the poky
repository and then check out the release branch:

Initializing the Build Environment

At this point, the mybuilds directory has
been created for you and it is now your current working directory.
If you do not provide your own directory name,
it defaults to build,
which is inside the Source Directory.

Configuring the local.conf File

Initializing the build environment creates a
conf/local.conf configuration file
in the Build Directory.
You need to manually edit this file to specify the machine you
are building and to optimize your build time.
Here are the minimal changes to make:

A good deal that goes into a Yocto Project build is simply
downloading all of the source tarballs.
Maybe you have been working with another build system
(OpenEmbedded or Angstrom) for which you have built up a sizable
directory of source tarballs.
Or, perhaps someone else has such a directory for which you have
read access.
If so, you can save time by adding statements to your
configuration file so that the build process checks local
directories first for existing tarballs before checking the
Internet.
Here is an efficient way to set it up in your
local.conf file:

In the previous example, the
BB_GENERATE_MIRROR_TARBALLS
variable causes the OpenEmbedded build system to generate tarballs
of the Git repositories and store them in the
DL_DIR
directory.
Due to performance reasons, generating and storing these tarballs
is not the build system's default behavior.

You can also use the
PREMIRRORS
variable.
For an example, see the variable's glossary entry in the
Yocto Project Reference Manual.

Building the Image

At this point, you need to select an image to build for the
Beaglebone hardware.
If this is your first build using the Yocto Project, you should try
the smallest and simplest image:

$ bitbake core-image-minimal

Now you just wait for the build to finish.

Here are some variations on the build process that could be helpful:

Fetch all the necessary sources without starting
the build:

$ bitbake -c fetchall core-image-minimal

This variation guarantees that you have all the sources for
that BitBake target should you disconnect from the net and
want to do the build later offline.

Specify to continue the build even if BitBake
encounters an error.
By default, BitBake aborts the build when it encounters an
error.
This command keeps a faulty build going:

$ bitbake -k core-image-minimal

Once you have your image, you can take steps to load and boot it on
the target hardware.